"Always be sincere, whether you mean it or not...."

Sincerity is overrated....

Generally speaking, the Rabbis view insincere deeds quite favorably. The Talmud writes often that it is better to learn or perform good deeds insincerely, for insincere deeds lead to sincere ones (Pesachim 50b). Better to "do" -- study Torah out of not-fully-committed curiosity, or perform mitzvos (commandments) for reward or recognition. The doing itself is valuable, in fact invaluable. Good deeds themselves wield an influence on a person and touch the soul.

Confucius taught the importance of sincerity not as an inherent character trait, but as a result of study and training.